The present invention relates to an electronic fuel injection system for otto engines with injection nozzle, adjustable throttle body disposed in a flow of intake air, and measurement of the mass of intake air.
In electronically regulated and controlled gasoline injection devices, the air ratio lambda is preadjusted in the manner that a corresponding mass flow of fuel is admixed with the mass flow of air. The closer the preadjustment of the air ratio approximates the value lambda=1, the less a lambda probe need enter into regulatory action in order to obtain the narrow "lambda window" necessary for optimal conversion of the noxious substances of the exhaust. This is particularly true in the case of rapidly varying engine loads and engine speeds of rotation.
In the known electronic injection systems, the flow of intake air is generally controlled by means of a throttle valve. For the metering of the fuel, the mass flow of air is determined by measurement devices such as measurement orifices or hot-wire probes. The control of the mass flow of air and the determination of the mass flow of air are thus effected by separate parts which, aside from the increased number of parts, results in a lack of sensitivity of response because the adjustment of the mass flow of fuel can take place only after the measurement of the mass of air. Aside from these basic disadvantages, the determination of the mass flow of air by a measurement orifice has the disadvantage of high mass inertia, large installation volume and high manufacturing costs. The measurement of the mass flow of air by a hot-wire air-quantity meter encounters difficulties due to the pulsating flow of air caused by the suction process of the fuel/air mixture via the cylinders. In addition to this, at certain speeds of rotation, resonance phenomena occur which can only be partially compensated for by engine-specific corrections.